The Twelfth Gordon Research Conference on the Chemistry and Biology of Pyrroles will focus on some recent research advances in the basic and clinical aspects of pyrrole compounds. This biennial conference, traditionally brings together a wide diversity of investigators, interested in the chemistry, biochemistry, molecular biology and genetics as well as clinical and industrial application and implications of pyrrole compounds. It is unquestionably, the only opportunity for such researchers who ordinarily would not find themselves at the same meeting, to exchange pertinent information with their international peers. The unusually diverse scientific composition of the formal program and the audience at large and the intimate and informal atmosphere are some of its fundamental strengths and attraction. The invited speakers include scientists from academia and research institutes from seven countries chosen on the basis of their scientific excellence and eminence in a given subfield of pyrrole research. A special effort has been made to include active junior as well as more established investigators as speakers. A large number of applicants to the conference is expected and approximately, 100 will be chosen according to three criteria: 1. Broad representation of disciplines and institutions; 2. Selection of women and young scientists; 3. Potential for significant contributions to discussions/poster sessions. The proposed program for this conference includes ten formal sessions. In an effort to maximize discussion, the formal program has been curtailed to five lectures/day, with the addition of two "invited poster discussions" sessions. We expect that the proposed conference will in a meaningful way further our fundamental understanding of the chemistry and biology of pyrroles as well as the underlying clinical defects and pathologies in their metabolism. Such knowledge we believe will permit greater strides in our approaches to clinical diagnosis and therapy. Funds are requested to cover travel costs and/or conference fees of some speakers, to enable them to attend the conference and thus to fulfill the goals proposed in this application. Without such funding, some of the speakers will not be able to participate in the conference.